1. Field of the Invention
The present invention relates to a surgical filament such as a surgical suture or ligature having improved surface-slipping characteristics, for example, having the ability to pass through the tissue and be tied.
2. Description of the Related Art
Various surgical filament's such as sutures and ligatures are used in surgery for the suturing, fixation and ligation of tissues including the internal organs, skin, muscles, bones, joints and blood vessels.
These surgical filaments are sometimes used for sutures and ligatures in the form of a monofilament. However, these filaments are often used in the form of multifilament or as a braided or twisted structure.
Even in the case of a monofilament having relatively good surface-slipping characteristics, untreated surfaces of the monofilament often exhibit insufficient smoothness. Consequently, tissue is sometimes damaged in the course of suturing or fixation by non-negligible friction between the filament and tissue. In order to prevent such trouble or to slide a knot of the suture to a desired position, various coatings are applied to the surgical filaments.
For example, Japanese Patent Publication SHO 60-25974(1985) discloses a synthetic multifilament suture covered with a mixture composed of a metal salt of a higher fatty acid and a bioabsorbable polymer. Japanese Laid-Open Patent SHO 61-76163(1986) describes a surgical filament dry-coated with a metal salt of a higher fatty acid.
The surgical filaments are, in the course of surgery, usually exposed to body fluids or passed through wet tissue from once to several times before making a knot.
When a conventionally known coating agent, for example, calcium stearate is coated on a bioabsorbable suture, a certain extent of the lubricating effect can be observed in the dry state. On the other hand, the surface-slipping characteristics are sometimes impaired in the wet state and thus it becomes difficult to slide a knot of the suture to the desired position. Additionally, there is a problem that passing the filament through the tissue is unsatisfactory.